With the development of electronic industries and the advance of industrial technologies, various electronic products are designed toward small size, light weightiness and easy portability. Consequently, these electronic products can be applied to mobile business, entertainment or leisure purposes whenever or wherever the users are. Recently, people pay much attention to the integrations and applications of mechanical, optical and electrical technologies. Consequently, a variety of optical devices such as image capturing devices or lighting devices are gradually and extensively applied to various electronic products (e.g., smart phones, wearable devices or other small-sized and portable electronic products). Consequently, according to the practical requirements, users can take the electronic products and use them whenever the users want. In other words, these electronic products not only have important commercial values but also provide more colorful lives to people.
With the improvement of the living quality, people's demands on more functions of the electronic products are gradually increased. Consequently, the demands on the optical devices of the electronic products are gradually increased. For meeting these demands, some micro spectrometers have been disclosed for acquiring the inherent information (e.g. ingredients, materials or properties) of an under-test object. For example, SCiO is a handheld molecular analyzer developed by Consumer Physics (an Israeli startup). The SCiO firstly projects a blue light onto the under-test object and then uses a near-infrared (NIR) technology to analyze the spectrum of the reflected light beams from the under-test object. Consequently, the ingredients of the under-test object (e.g., the calorie of food or the sugar content) or the plant growth conditions can be acquired.
In the related fields, other companies develop similar micro spectrometers. For example, the similar micro spectrometers include the Appllo sensor/nano spectrum-on-a-chip developed by Nano λ (nanolambda) of Korea, the micro spectrometer developed by Hamamatsu of Japan, and so on. Moreover, the micro spectrometer developed by Hamamatsu of Japan, e.g., C12666MA micro spectrometer, only has the element of receiving light beams but does not have the element of outputting light beams.
However, the conventional micro spectrometer has some drawbacks. For example, the signal-to-noise ratio (S/N ratio) is low, and the overall thickness fails to be effectively reduced. Since the pattern of the light beams projected on the under-test object is monotonous, the amount of inherent information obtained through the spectrum response analysis is limited. Therefore, the conventional technology needs to be further improved.